I just ran into what appears to be a minor bug with sub-brackets when condensing is turned on.
Start a new project and add some solo woodwind players: two flutes, two oboes, two clarinets, and two bassoons. Dorico will correctly sub-bracket each type of instrument. Now switch to Write Mode and add key signature, time signature, and a bunch of bars. Turn on condensing. The bottom sub-bracketed group (the bassoons) have lost their sub-bracket. Turn off condensing, and the bassoon sub-bracket re-appears. The only way to make it appear when condensing is turned on is to delete the bassoon sub-bracket in Engrave Mode (with condensing turned off), and then re-apply the sub-bracket.
It doesn’t seem to matter how many sub-bracketed instruments there are in a given bracketed group – it’s always the bottom sub-bracket that goes missing when you turn on condensing.